Survey of Smokers Among Workers at One Facility: A Cross-sectional Study With Propensity Score Matching.

BACKGROUND/AIM: Smoking has been reported to be a risk factor for a variety of diseases. In Japan, the Brief Job Stress Questionnaire (BJSQ) has been administered by the Ministry of Health, Labour and Welfare since December 2015, but few reports have focused on its relationship with smoking. We investigated the current situation of smokers among staff of Kagoshima University who underwent a medical check-up. PATIENTS AND METHODS: Of 2,478 people who underwent a medical check-up in May and June 2021, we targeted 2,237 workers who reported whether they smoked. We examined results of the medical check-up and BJSQ and the background of smokers (n=139, 6.2%). We compared smokers and non-smokers (n=2,098) using propensity score matching (PSM) for sex, age, drinking habits, medication for dyslipidaemia, and overtime working hours at a 1:1 ratio. RESULTS: The results showed that white blood cell count (p=0.044), platelet count (p<0.001), glutamyl transferase (p=0.023), and triglyceride (p=0.027) were significantly higher among current smokers in comparison with current non-smokers. Smokers reported significantly more stress than non-smokers in terms of social support (p=0.027). CONCLUSION: As a result of PSM, several blood test items related to non-communicable diseases (lifestyle-related diseases) showed high values in current smokers, and these individuals reported significantly more stress than non-smokers. According to the emphasis on group analysis in the Total Health Promotion Plan revised in 2020, our findings can be helpful in enhancing smoking cessation programs in the workplace.

Clinical features of obscure gastrointestinal bleeding undergoing capsule endoscopy: A retrospective cohort study.

BACKGROUND: Capsule endoscopy has been widely used to investigate obscure gastrointestinal bleeding (OGIB) in the small intestine since its approval in 2001. However, the clinical features of OGIB remain unclear. AIM: We retrospectively examined the clinical features and risk factors of OGIB in patients who underwent capsule endoscopy in our hospital. METHODS: We included 420 of the 431 patients who underwent capsule endoscopy from June 2014 to May 2021, in whom the small intestine could be observed. We retrospectively compared the clinical features and treatment of OGIB cases, with or without active small bowel bleeding (n = 173), with other cases (n = 247). Patient sex, age, diabetes mellitus, and heart failure histories were matched for the analysis. RESULTS: The male/female ratio was 247/173 and the average age was 51.54 years. In multivariate analysis, the use of direct oral anticoagulants was significant (P = 0.016), and vascular lesions (P = 0.018) were observed in OGIB cases. When OGIB cases with and without active small bowel bleeding were compared, serum albumin level was lower in cases with active bleeding (P = 0.031). When treatment of OGIB cases were compared, those without vascular lesions could be treated conservatively (P = 0.0047). In the 1:1 propensity score matching analysis, serum creatinine level was elevated in cases of active bleeding (P = 0.029), and cases without vascular lesions were treated conservatively (P = 0.010). CONCLUSIONS: Use of direct oral anticoagulants is frequently associated with OGIB. OGIB patients without vascular lesions may be treated conservatively.

Inhibition of ABL1 tyrosine kinase reduces HTLV-1 proviral loads in peripheral blood mononuclear cells from patients with HTLV-1-associated myelopathy/tropical spastic paraparesis.

Human T-cell leukemia virus type 1 (HTLV-1) causes incurable adult T-cell leukemia and HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP). Patients with HAM/TSP have increased levels of HTLV-1-infected cells compared with asymptomatic HTLV-1 carriers. However, the roles of cellular genes in HTLV-1-infected CD4+ T cells await discovery. We performed microarray analysis of CD4+ T cells from HAM/TSP patients and found that the ABL1 is an important gene in HAM/TSP. ABL1 is a known survival factor for T- and B-lymphocytes and is part of the fused gene (BCR-ABL) known to be responsible for chronic myelogenous leukemia (CML). ABL1 tyrosine kinase inhibitors (TKIs), including imatinib, nilotinib, and dasatinib, are used clinically for treating CML. To evaluate whether ABL1 is indeed important for HAM/TSP, we investigated the effect of TKIs on HTLV-1-infected cells. We developed a propidium monoazide-HTLV-1 viability quantitative PCR assay, which distinguishes DNA from live cells and dead cells. Using this method, we were able to measure the HTLV-1 proviral load (PVL) in live cells alone when peripheral blood mononuclear cells (PBMCs) from HAM/TSP cases were treated with TKIs. Treating the PBMCs with nilotinib or dasatinib induced significant reductions in PVL (21.0% and 17.5%, respectively) in live cells. Furthermore, ABL1 siRNA transfection reduced cell viability in HTLV-1-infected cell lines, but not in uninfected cell lines. A retrospective survey based on our clinical records found a rare case of HAM/TSP who also suffered from CML. The patient showed an 84.2% PVL reduction after CML treatment with imatinib. We conclude that inhibiting the ABL1 tyrosine kinase specifically reduced the PVL in PBMCs from patients with HAM/TSP, suggesting that ABL1 is an important gene for the survival of HTLV-1-infected cells and that TKIs may be potential therapeutic agents for HAM/TSP.

Potential predictors of susceptibility to occupational stress in Japanese novice nurses - a pilot study.

BACKGROUND: Occupational stress is a known factor behind employee resignations; thus, early identification of individuals prone to such stress is important. Accordingly, in this pilot study we evaluated potential predictors of susceptibility to occupational stress in Japanese novice nurses. METHODS: Forty-two female novice nurses at Kagoshima University Hospital were recruited for the study population. Each underwent physical health and urinary examinations, and completed a lifestyle questionnaire at the time of job entry. Each also completed a Brief Job Stress Questionnaire (BJSQ), related to mental health status, at job entry and 5 months post-entry. Psychological stress, somatic symptoms, and combined BJSQ scores were determined for each time point. RESULTS: All three stress condition scores had significantly decreased at 5 months post-entry, suggesting occupational stress. Systolic blood pressure (r = -0.324, p < 0.05) and urinary sodium (r = -0.313, p < 0.05) were significantly negatively correlated with combined BJSQ score at 5 months post-entry. Post-entry stress condition scores were significantly low in subjects reporting substantial 1-year body weight change (≤ ± 3 kg) and short times between dinner and bedtimes (≤2 h), though baseline stress condition scores were not. Urinary sodium concentration, 1-year body weight change, and pre-sleep evening meals were then targeted for multivariate analysis, and confirmed as independent explanatory variables for post-entry stress condition scores. CONCLUSIONS: One-year body weight change, times between dinner and bedtimes, and urinary sodium concentration are promising potential predictors of susceptibility to occupational stress, and should be further investigated in future research. TRIAL REGISTRATION: ISRCTN ISRCTN17516023. Retrospectively registered 7 December 2016.

[Experimental Approach to Analysis of the Relationship between Food Environments and Lifestyle-Related Diseases, Including Cardiac Hypertrophy, Fatty Liver, and Fatigue Symptoms].

The food habit is involved in the onset and development of lifestyle-related diseases. In this review I would like to describe a historical case of vitamin B1 deficiency, as well as our case study of fatty acid metabolism abnormality due to carnitine deficiency. In history, the army and navy personnel in Japan at the end of the 19th century received food rations based on a high-carbohydrate diet including white rice, resulting in the onset of beriberi. An epidemiological study by Kenkan Takaki revealed the relationship between the onset of beriberi and rice intake. Then, Takaki was successful in preventing the onset of beriberi by changing the diet. However, the primary cause had yet to be elucidated. Finally, Christian Eijkman established an animal model of beriberi (chickens) showing peripheral neuropathy, and he identified the existence of an anti-beriberi substance, vitamin B1. This is an example of the successful control of a disease by integrating the results of epidemiological and experimental studies. In our study using a murine model of fatty acid metabolism abnormality caused by carnitine deficiency, cardiac abnormality and fatty liver developed depending on the amount of dietary fat. In addition, the mice showed disturbance of orexin neuron activity related to the sleep-arousal system, which is involved in fatigue symptoms under fasting condition, one of the states showing enhanced fatty acid metabolism. These findings suggest that fatty acid toxicity is enhanced when the mice are more dependent on fatty acid metabolism. Almost simultaneously, a human epidemiological study showed that narcolepsy, which is caused by orexin system abnormality, is associated with the polymorphism of the gene coding for carnitine palmitoyltransferase 1B, which is involved in carnitine metabolism. To understand the pathological mechanism of fatty acid toxicity, not only an experimental approach using animal models, but also an epidemiological approach is necessary. The results will be applied to preventing and treating lifestyle-related diseases associated with fatty acid metabolism abnormality.

Effect of myeloperoxidase inhibition on gene expression profiles in HL-60 cells exposed to 1,2,4,-benzenetriol.

While it is known that benzene induces myeloid leukemia in humans, the mechanism has yet to be clarified. Previously, we suggested that myeloperoxidase (MPO) was the key enzyme because it promotes generation of powerful oxidant hypochlorous acid (HOCl) which, reacting with DNA, causes leukemogenesis. In this study, using a whole-human-genome oligonucleotide microarray to clarify the relationships between myelotoxicity of benzene and MPO, we analyzed the genome-wide expression profiles of HL-60 human promyelocytic cell lines exposed to 1,2,4-benzenetriol (BT) with or without MPO inhibition. The microarray analysis revealed that short (1 h) and longer (4 h) exposure to BT changed the expression in HL-60 cells of 1,213 or 1,214 genes associated with transcription, RNA metabolic processes, immune response, apoptosis, cell death, and biosynthetic processes (|Z-score|> 2.0), and that these changes were dramatically lessened by MPO-specific inhibition. The presence of functionally important genes and, specifically, genes related to apoptosis, carcinogenesis, regulation of transcription, immune responses, oxidative stress, and cell-cycle regulation were further validated by real-time RT-PCR. Gene expression profiles along with Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway annotation analysis suggest that BT-induced DNA halogenation by MPO is a primary reaction in the leukemogenesis associated with benzene.

Snail modulates cell metabolism in MDCK cells.

Snail, a repressor of E-cadherin gene transcription, induces epithelial-to-mesenchymal transition and is involved in tumor progression. Snail also mediates resistance to cell death induced by serum depletion. By contrast, we observed that snail-expressing MDCK (MDCK/snail) cells undergo cell death at a higher rate than control (MDCK/neo) cells in low-glucose medium. Therefore, we investigated whether snail expression influences cell metabolism in MDCK cells. Although gylcolysis was not affected in MDCK/snail cells, they did exhibit reduced pyruvate dehydrogenase (PDH) activity, which controls pyruvate entry into the tricarboxylic acid (TCA) cycle. Indeed, the activity of multiple enzymes involved in the TCA cycle was decreased in MDCK/snail cells, including that of mitochondrial NADP(+)-dependent isocitrate dehydrogenase (IDH2), succinate dehydrogenase (SDH), and electron transport Complex II and Complex IV. Consequently, lower ATP content, lower oxygen consumption and increased survival under hypoxic conditions was also observed in MDCK/snail cells compared to MDCK/neo cells. In addition, the expression and promoter activity of pyruvate dehydrogenase kinase 1 (PDK1), which phosphorylates and inhibits the activity of PDH, was increased in MDCK/snail cells, while expression levels of glutaminase 2 (GLS2) and ATP-citrate lyase (ACLY), which are involved in glutaminolysis and fatty acid synthesis, were decreased in MDCK/snail cells. These results suggest that snail modulates cell metabolism by altering the expression and activity of key enzymes. This results in enhanced glucose dependency and leads to cell death under low-glucose conditions. On the other hand, the reduced requirements for oxygen and nutrients from the surrounding environment, might confer the resistance to cell death induced by hypoxia and malnutrition.

Benzene metabolite 1,2,4-benzenetriol induces halogenated DNA and tyrosines representing halogenative stress in the HL-60 human myeloid cell line.

BACKGROUND: Although benzene is known to be myelotoxic and to cause myeloid leukemia in humans, the mechanism has not been elucidated. OBJECTIVES: We focused on 1,2,4-benzenetriol (BT), a benzene metabolite that generates reactive oxygen species (ROS) by autoxidation, to investigate the toxicity of benzene leading to leukemogenesis. METHODS: After exposing HL-60 human myeloid cells to BT, we investigated the cellular effects, including apoptosis, ROS generation, DNA damage, and protein damage. We also investigated how the cellular effects of BT were modified by hydrogen peroxide (H2O2) scavenger catalase, hypochlorous acid (HOCl) scavenger methionine, and 4-aminobenzoic acid hydrazide (ABAH), a myeloperoxidase (MPO)-specific inhibitor. RESULTS: BT increased the levels of apoptosis and ROS, including superoxide (O2•-), H2O2, HOCl, and the hydroxyl radical (•OH). Catalase, ABAH, and methionine each inhibited the increased apoptosis caused by BT, and catalase and ABAH inhibited increases in HOCl and •OH. Although BT exposure increased halogenated DNA, this increase was inhibited by catalase, methionine, and ABAH. BT exposure also increased the amount of halogenated tyrosines; however, it did not increase 8-oxo-deoxyguanosine. CONCLUSIONS: We suggest that BT increases H2O2 intracellularly; this H2O2 is metabolized to HOCl by MPO, and this HOCl results in possibly cytotoxic binding of chlorine to DNA. Because myeloid cells copiously express MPO and because halogenated DNA may induce both genetic and epigenetic changes that contribute to carcinogenesis, halogenative stress may account for benzene-induced bone marrow disorders and myeloid leukemia.

Effect of habitual exercise on renal carcinogenesis by ferric nitrilotriacetate.

OBJECTIVES: We investigated whether habitual exercise (HE) (treadmill running) suppresses development of renal cell carcinoma (RCC) induced by ferric nitrilotriacetate (Fe-NTA). METHODS: Male Fischer 344 rats were divided into six groups: group I, saline treatment (12 weeks = initiation period) and non-HE; group II, Fe-NTA treatment (12 weeks) and non-HE; group III, saline treatment and short-term (12 weeks) HE; group IV, Fe-NTA treatment and short-term HE; group V, saline treatment and long-term (40 weeks) HE; and group VI, Fe-NTA treatment and long-term HE. Saline treatment groups did not develop RCC, therefore we investigated the effects of HE among Fe-NTA treatment groups. RESULTS: Gross nodules (diagnosed as RCC), RCC represented by microcarcinomas (Mcs), karyomegalic cells (KCs), and degenerative tubules (DTs) were seen in rats treated with Fe-NTA. The number of Mcs, KCs, and DTs were increased in the short-term HE group when compared with those in the non-HE group, but were decreased in the long-term HE group when compared with those in the short-term HE group. CONCLUSIONS: Short-term (initiation period) HE promoted renal carcinogenesis induced by Fe-NTA; however, long-term HE after the initiation period suppressed the promoted carcinogenesis.

Benzene induces cytotoxicity without metabolic activation.

OBJECTIVES: Benzene has been consistently associated with hematological disorders, including acute myeloid leukemia and aplastic anemia, but the mechanisms causing these disorders are still unclear. Various metabolites of benzene lead to toxicity through the production of reactive oxygen species (ROS), the inhibition of topoisomerase and DNA damage. However, benzene itself is considered to have no mutagenic or cytotoxic activity. In this study, we investigated the effects of benzene itself on a human myeloid cell line with or without benzene metabolizing enzyme inhibitors. METHODS: A human myeloid cell line, HL-60, was exposed to benzene with or without cytochrome P450 2E1 or myeloperoxidase inhibitor. Cytotoxicity was evaluated in terms of global DNA methylation levels, induction of apoptosis, and ROS production. RESULTS: Benzene did not change global DNA methylation levels. However, benzene itself increased the levels of apoptosis and ROS. This cytotoxicity did not change with the addition of benzene metabolizing enzyme inhibitors. Benzene itself increased the mRNA levels of oxidative stress-related genes and transcription factors of activator protein-1. CONCLUSIONS: Benzene did not influence global DNA methylation in HL-60 cells, but had cytotoxic effects and changed gene expression levels. To elucidate the mechanisms of benzene toxicity, benzene itself as well as benzene metabolites must be investigated.

Environmental mutagens may be implicated in the emergence of drug-resistant microorganisms.

The emergence of drug-resistant microorganisms is an important medical and social problem. Drug-resistant microorganisms are thought to grow selectively in the presence of antibiotics. Most clinically isolated drug-resistant microorganisms have mutations in the target genes for the drugs. While any of the many mutagens in the environment may cause such genetic mutations, no reports have yet described whether these mutagens can confer drug resistance to clinically important microorganisms. We investigated how environmental mutagens might be implicated in acquired resistance to antibiotics in clinically important microorganisms, which causes human diseases. We selected mutagens found in the environment, in cigarette smoke, or in drugs, and then exposed Pseudomonas aeruginosa to them. After exposure, the incidence of rifampicin- and ciprofloxacin-resistant P. aeruginosa strains markedly increased, and we found mutations in genes for the antibiotic-target molecule. These mutations were similar to those found in drug-resistant microorganisms isolated from clinical samples. Our findings show that environmental mutagens, and an anticancer drug, are capable of inducing drug-resistant P. aeruginosa similar to strains found in clinical settings.

Dehydroepiandrosterone increased oxidative stress in a human cell line during differentiation.

Dehydroepiandrosterone (DHEA), a reversible inhibitor of glucose-6-phosphate dehydrogenase (G6PD), is increasingly taken as an antioxidative and anti-ageing supplement. This study investigated the effects of DHEA on the expression of G6PD and on the state of oxidative stress in a human promyelocytic leukaemia cell line, HL60, during the differentiation to neutrophil-like cell. This study differentiated HL60 with dimethyl sulfoxide (DMSO) in the presence (DMSO-HL60/DHEA) or absence (DMSO-HL60) of DHEA. During the differentiation, activity, mRNA and protein levels of G6PD were increased. DHEA increased these levels further. DHEA by itself suppressed the production of superoxide from DMSO-HL60 upon stimulation with phorbol myristate acetate (PMA). However, DMSO-HL60/DHEA stimulated with PMA in the absence of DHEA produced superoxide and 8-oxo-deoxyguanosine more than PMA-stimulated DMSO-HL60. After addition of H(2)O(2), the ratio of reduced glutathione to oxidized glutathione was lower in DMSO-HL60/DHEA than in DMSO-HL60. These findings indicate that DHEA acts both as an antioxidant and as a pro-oxidant.

Involvement of reactive oxygen species in Microcystin-LR-induced cytogenotoxicity.

Microcystin-LR (MCLR) is a potent hepatotoxin. Oxidative stress is thought to be implicated in the cytotoxicity of MCLR, but the mechanisms by which MCLR produces reactive oxygen species (ROS) are still unclear. This study investigated the role and possible sources of ROS generation in MCLR-induced cytogenotoxicity in HepG2, a human hepatoma cell line. MCLR increased DNA strand breaks, 8-hydroxydeoxiguanosine formation, lipid peroxidation, as well as LDH release, all of which were inhibited by ROS scavengers. ROS scavengers partly suppressed MCLR-induced cytotoxicity determined by the MTT assay. MCLR induced the generation of ROS, as confirmed by confocal microscopy with 2-[6-(4'-hydroxy)phenoxy-3H-xanthen-3-on-9-yl]benzoic acid, and upregulated the expression of CYP2E1 mRNA. In addition, CYP2E1 inhibitors chlormethiazole and diallyl dulphide inhibited both ROS generation and cytotoxicity induced by MCLR. The results suggest that ROS contribute to MCLR-induced cytogenotoxicity. CYP2E1 might be a potential source responsible for ROS generation by MCLR.

Citrin/mitochondrial glycerol-3-phosphate dehydrogenase double knock-out mice recapitulate features of human citrin deficiency.

Citrin is the liver-type mitochondrial aspartate-glutamate carrier that participates in urea, protein, and nucleotide biosynthetic pathways by supplying aspartate from mitochondria to the cytosol. Citrin also plays a role in transporting cytosolic NADH reducing equivalents into mitochondria as a component of the malate-aspartate shuttle. In humans, loss-of-function mutations in the SLC25A13 gene encoding citrin cause both adult-onset type II citrullinemia and neonatal intrahepatic cholestasis, collectively referred to as human citrin deficiency. Citrin knock-out mice fail to display features of human citrin deficiency. Based on the hypothesis that an enhanced glycerol phosphate shuttle activity may be compensating for the loss of citrin function in the mouse, we have generated mice with a combined disruption of the genes for citrin and mitochondrial glycerol 3-phosphate dehydrogenase. The resulting double knock-out mice demonstrated citrullinemia, hyperammonemia that was further elevated by oral sucrose administration, hypoglycemia, and a fatty liver, all features of human citrin deficiency. An increased hepatic lactate/pyruvate ratio in the double knock-out mice compared with controls was also further elevated by the oral sucrose administration, suggesting that an altered cytosolic NADH/NAD(+) ratio is closely associated with the hyperammonemia observed. Microarray analyses identified over 100 genes that were differentially expressed in the double knock-out mice compared with wild-type controls, revealing genes potentially involved in compensatory or downstream effects of the combined mutations. Together, our data indicate that the more severe phenotype present in the citrin/mitochondrial glycerol-3-phosphate dehydrogenase double knock-out mice represents a more accurate model of human citrin deficiency than citrin knock-out mice.

Fasting-induced reduction in locomotor activity and reduced response of orexin neurons in carnitine-deficient mice.

We found reduced locomotor activity (LA) under fasting in systemic carnitine-deficient juvenile visceral steatosis (jvs(-/-)) mice. When food was withdrawn at 8:00 a.m. (lights-off at 7:00 p.m., 12h/cycle), the nocturnal LA of jvs(-/-) mice was much less than the control (jvs(+/+) and jvs(+/-)) mice. LA recovered under carnitine or sucrose administration, but not under medium-chain triglyceride. In addition, fasted jvs(-/-) mice, without any energy supply, were activated by modafinil, a stimulator of the dopamine pathway. These results suggest that the reduced LA is not adequately explained by energy deficit. As the fasted jvs(-/-) mice showed lower body core temperature (BT), we examined the central nervous system regulating LA and BT. We found lower percentage of c-Fos positive orexin neurons in the lateral hypothalamus and reduced orexin-A concentration in the cerebrospinal fluid of fasted jvs(-/-) mice. Sleep analysis revealed that fasted jvs(-/-) mice had disruption of prolonged wakefulness, with a higher frequency of brief episodes of non-REM sleep during the dark period than fasted jvs(+/+) mice. These results strongly suggest that the reduced LA in fasted jvs(-/-) mice is related to the inhibition of orexin neuronal activity.

Pyruvate ameliorates the defect in ureogenesis from ammonia in citrin-deficient mice.

BACKGROUND/AIMS: Mutations in SLC25A13, encoding the mitochondrial aspartate-glutamate carrier citrin, cause adult-onset type II citrullinemia (CTLN2) in humans. We have previously reported that although citrin-knockout (Ctrn-/-) mice fail to display symptoms of CTLN2, liver perfusion revealed a deficit in ureogenesis from ammonia accompanied by an increase in the perfusate lactate-to-pyruvate (L/P) ratio. The present study explores the effects of pyruvate, aspartate and citrate on improving the abnormalities observed in the Ctrn-/- liver. METHODS: We measured the rate of ureogenesis from ammonium chloride using the liver-perfusion system. RESULTS: Pyruvate infusion lowered the L/P ratio and corrected the deficit in ureogenesis in the Ctrn-/- liver. This effect was found to be dose-dependent in both instances. Phenazine methosulfate, a cytosolic oxidant, also improved the rate of ureogenesis in the Ctrn-/- liver and led to a fall in the L/P ratio. The addition of aspartate or citrate did not change either the rate of ureogenesis or the L/P ratio in the Ctrn-/- liver. CONCLUSIONS: Citrin deficiency disturbs urea synthesis primarily as a result of an elevated cytosolic NADH/NAD+ ratio owing to limited reoxidation of reducing equivalents. Clinically, pyruvate may have a therapeutic benefit for CTLN2 patients.

Tetrodotoxin-resistant Na+ channels in human neuroblastoma cells are encoded by new variants of Nav1.5/SCN5A.

Both tetrodotoxin-sensitive (TTX-S) and TTX-resistant (TTX-R) voltage-dependent Na+ channels are expressed in the human neuroblastoma cell line NB-1, but a gene encoding the TTX-R Na+ channel has not been identified. In this study, we have cloned cDNA encoding the alpha subunit of the TTX-R Na+ channel in NB-1 cells and designated it hNbR1. The longest open reading frame of hNbR1 (accession no. AB158469) encodes 2016 amino acid residues. Sequence analysis has indicated that hNbR1 is highly homologous with human cardiac Nav1.5/SCN5A with > 99% amino acid identity. The presence of a cysteine residue (Cys373) in the pore-loop region of domain I is consistent with the supposition that hNbR1 is resistant to TTX. Analysis of the genomic sequence of SCN5A revealed a new exon encoding S3 and S4 of domain I (exon 6A). In addition, an alternative splicing variant, lacking exon 18, that encodes 54 amino acids in the intracellular loop between domains II and III was found (hNbR1-2; accession no. AB158470). Na+ currents in human embryonic kidney cells (HEK293) transfected with hNbR1 or hNbR1-2 showed electrophysiological properties similar to those for TTX-R I(Na) in NB-1 cells. The IC50 for the TTX block was approximately 8 microM in both variants. These results suggest that SCN5A has a newly identified exon for alternative splicing and is more widely expressed than previously thought.

Adult-onset type II citrullinemia and idiopathic neonatal hepatitis caused by citrin deficiency: involvement of the aspartate glutamate carrier for urea synthesis and maintenance of the urea cycle.

Citrin is a mitochondrial aspartate glutamate carrier primarily expressed in the liver, heart, and kidney. We found that adult-onset type II citrullinemia is caused by mutations in the SLC25A13 gene that encodes for citrin. In this report, we describe the frequency of SLC25A13 mutations, the roles of citrin as a member of the urea cycle and as a member of the malate-aspartate shuttle, the relationship between its functions and symptoms of citrin deficiency, and therapeutic issues.

Novel mRNA molecules are induced in hypertrophied ventricles of carnitine-deficient mice and belong to a family of up-regulated gene in cells overexpressing c-erbB-2.

To clarify the pathogenesis of cardiac hypertrophy in carnitine-deficient juvenile visceral steatosis (JVS) mice, we performed differential mRNA display analysis with the ventricles of control and JVS mice. We found a novel up-regulated gene, designated as carnitine deficiency-associated gene expressed in ventricle (CDV)-3. Northern blot analysis with a cDNA probe derived from the novel gene revealed two substantial mRNA species of prominent 4.1- and faint 3.5-kb in examined tissues of control and JVS mice. In spite of their widely expressed features, up-regulation of the gene was found predominantly in the ventricles and slightly in the auricles and skeletal muscles of JVS mice. The up-regulation of CDV-3 gene in the ventricles of JVS mice was significantly relieved by carnitine administration within 6 h. The entire cDNA nucleotide sequences showed that two kinds of cDNA, long and short versions (CDV-3A and -3B), corresponding to the detected mRNAs, are different in a 711 base fragment. Analysis of genomic DNA revealed that the two mRNAs were derived from a single CDV-3 gene with five exons by alternative splicing. The deduced amino acid sequences indicated that the isoforms consist of 236 and 281 residues, differing at regions near the carboxy-terminus but sharing 231 residues of the amino-terminal regions. A BLAST search revealed that they show a high similarity to a human predicted nuclear protein (H41), which has been reported to be up-regulated in breast cancer cells overexpressing cellular-erythroblastosis B-2 (c-erbB-2, a kind of tyrosine kinase).We report the identification and characterization of novel transcripts that may be involved in the development of cardiac hypertrophy caused by carnitine deficiency.